1. Field of the Invention
This invention relates to a vent valve which is connected, for example, to a vent pipe serving to discharge water for the purpose of relieving the negative pressure generated in the pipe and is made to permit removal of an inner part thereof for the sake of inspection, for example.
2. Description of the Related Art
A vent valve is intended to enable an expansion vent pipe laid inside a building to aspirate air, mainly during the discharge of water, without requiring the terminal of the pipe to open directly into the ambient air. It has been proposed in various valve constructions.
The vent valve illustrated in FIG. 21, for the purpose of precluding the phenomenon that a valve body 3 is disabled to produce a closing motion when the dew drops in a valve chamber 1 are suffered to freeze, adopts a construction having a groove 4 for collecting the dew drops. A flow path 6 establishes communication between the groove 4 and a body 5 having a pipe shape, and is consequently adapted to allow escape of the dew drops into the body 5. In this case, the flow path 6 is formed in the shape of a cave with the object of enabling concentric valve seats 2 and 7 to form simple annular circles.
JP-B-01-37,628 discloses an example of forming a flow path in the shape of a groove in addition to an example of forming it in the shape of a cave as in the example cited above. In the construction of this prior art, concentric valve seats do not form perfectly annular circles because the flow path of the shape of a groove is formed in the lateral direction on the concentric valve seats and the valve seats are partly cut by the flow path.
The safety valve disclosed in JP-B-01-37,628 has a cap adapted so as to be set fast around the cylinder of the valve for sealing the valve and, when necessary, removed from the cylinder. The connecting valve taught in JP-B-01-35,235 has a construction which is provided with a pipe connector extended from the main body of the connecting valve and joined by means of a screw to an external flow path.
In the case of the vent valve illustrated in FIG. 21, since it has the flow path 6 formed in the shape of a cave for the sake of securing the valve seats 2 and 7 which constitute annular circles, however, it requires a slide type metal die for forming the main body of the vent valve from a resin. The cost of the metal die inevitably results in boosting the cost of the vent valve. Further, since a housing 10 forming the valve chamber 1 must be segmented below the flow path 6, a fitting part 8 between the body 5 and the housing 10 necessitates junction by adhesion lest the segmenting part should be accidentally resolved during the course of working. The junction by adhesion, therefore, not only adds to the number of steps of production but also boosts the cost and entails the possibility that the dew drops will leak through the part of junction of the fitting part 8. The dew drops, when frozen, will expand the housing 10 and leak through the junction part. Further, since the fitting part 8 is exposed to the exterior through an insulating member 9, the vent valve possibly sacrifices airtightness, suffers the valve body 3 to actuate under only feeble negative pressure, and gives rise to leakage of offensive smell through this exposed part.
Since the fitting part 8 coupling the body 5 and housing 10 is joined thereto by adhesion lest the union should be accidentally resolved during the courseof working, inner parts of the valve body 3 are incapable of being taken out while in service to be inspected or repaired such as by washing.
The vent valve of JP-B-01-37,628, which has no need for the structure of a slide type metal die, is constructed to seal itself solely with the weight of the valve body by utilizing the elasticity of a rubber packing and, accordingly, is provided with a groove which is laid in the lateral direction on the annular circles of the valve seats. It, therefore, entails the problem that if the packing collides against the part embracing the groove, it will be prevented from manifesting a satisfactory elastic deformation to the valve seats. As a result, it will exhibit only an impaired property of following the valve seats, and rather suffers from degradation of the sealing property.
Further, notwithstanding that the cap is adapted to be removed from the housing, the prior art relevant to this vent valve discloses no technical matters concerning a means to attach and detach the cap or the ability of the cap to seal the housing. Even if the inner parts of the valve body are taken out and inspected, the cap and the valve body are devoid of means to follow one another. Thus, the vent valve is at a disadvantage in requiring the cap and the valve body to be removed by operations performed independently of each other and compelling the operator to carry out extremely troublesome works.
When an instrument (vent valve) is installed at the terminal of an expansion vent pipe inside a building, the building is expected to be furnished with an inspection hole for permitting inspection of the instrument. The conventional instrument of this sort is either incapable of being disassembled at all for inspection or capable of being disassembled veritably incompletely as pointed out above.
Recently, therefore, the practice of first providing the vent pipe at the terminal thereof with a removable tube, disposing a given instrument (vent valve) in such a manner as to be attached to or detached from the removable tube and, when the instrument stands in need of a repair work, effecting replacement of the instrument with a spare one through the removable tube has been in vogue. This method, however, does not deserve designation as a rational approach because the removable tube calls for extra cost.
The connecting valve according to JP-B-01-35,235, on reaching the point where it is required to be replaced on account of the wear of the interior thereof, must be replaced wholly together with the joint of the pipe connector, and consequently entails an otherwise unnecessary cost. Further, since this connecting valve is provided below an external ring and near a valve seat with a connecting part which operates with a screw, it has the possibility that the dew drops will leak through the connecting part and the dew drops, when frozen, will expand the outer ring and leak through the connecting part.
This invention has been perfected as a result of a diligent study pursued in view of the true state of the prior art mentioned above. It is an object of this invention to provide a vent valve which, by deflecting the axis of a connecting pipe connected to a vent pipe used for discharging water from the axis of a valve chamber to thereby allow formation of a flow path serving to establish communication between a water collecting groove in the valve chamber and the connecting pipe by means of a simple two-plate type metal die, is enabled to lower the cost of manufacture, manifest a satisfactory ability to seal, prevent inner parts from producing defective functions, and make effective use of the space for installation. It is also an object of this invention to rely on the simplicity of construction to facilitate the operation of disassembling the inner parts. Another object of this invention consists in providing a vent valve which excels particularly in the tightness of its seal and features the fact that a small space suffices for its installation in addition to being at an advantage in obviating the necessity for replacing the valve wholly and facilitating the operation of cleaning and replacing the mechanism in the valve after the valve has been worn out.